Registration Dossier

Environmental fate & pathways

Adsorption / desorption

Currently viewing:

Administrative data

Link to relevant study record(s)

Reference
Endpoint:
adsorption / desorption: screening
Data waiving:
study scientifically not necessary / other information available
Justification for data waiving:
the study does not need to be conducted because the substance has a low octanol water partition coefficient and the adsorption potential of this substance is related to this parameter

Description of key information

(4-methylphenyl)silanetriol (hydrolysis product): Log Koc = 0.708 (QSAR)

Key value for chemical safety assessment

Koc at 20 °C:
5.11

Additional information

Trichloro(4-methylphenyl)silane (CAS 701-35-9) hydrolyses rapidly in water to (4-methylphenyl)silanetriol and hydrochloric acid (half-life < 1 min at 1.5 °C and pH 4-7). Since the parent compound is not stable in the environment, the hydrolysis products were further assessed for adsorption according to ECHA guidance for Chemical Safety Assessment (Chapter R.16, 2016). The silanol hydrolysis product has a low octanol–water partition coefficient (-0.6 based on QSAR) and thus low potential for adsorption. In accordance with Regulation (EC) No 1907/2006, Annex VIII, 9.3.1., column 2, the adsorption/desorption screening test does not need to be conducted. Nevertheless further information on the adsorption behavior of the silanol hydrolysis product was collected by appropriate calculations for the purposes of the environmental exposure assessment. The partitioning coefficient log Koc was calculated using the TGD (Technical Guidance Document) non-hydrophobics log Kow prediction method (EC, 2003). The calculated Koc is 5.11 (log Koc of 0.708) for the silanol hydrolysis product. Adsorption potential of the other hydrolysis product hydrochloric acid can be neglected (OECD SIDS 2002).

Reference:

EC (2003). European Union Technical Guidance Document on Risk Assessment for New and Existing Substances, Part II, European Chemicals Bureau, 2003.

OECD (2002): SIDS Initial Assessment Report for SIAM 15, Boston, USA, 22-25 October 2002, Hydrogen chloride, CAS 7647-01-0.

[LogKoc: 0.708]